Distributed vibration measurement device and method based on weak grating array and pulse coding

Abstract

The invention provides a distributed vibration measurement device and method based on a weak grating array and pulse coding. The device comprises a laser light source, a first coupler, an arbitrary waveform generator, an acousto-optic modulator, a circulator, the weak grating array, a second coupler and a data processing module. The laser light source generates continuous light; the first coupler divides the continuous light into signal light and local oscillation light; the arbitrary waveform generator generates four groups of target electric pulse sequences based on a zero insertion coding mode; the acousto-optic modulator modulates the signal light into a Gray code pulse sequence according to the target electric pulse sequence; the circulator inputs the Gray coding pulse sequence into the weak grating array; the weak grating array generates four groups of reflection signals according to the Gray coding pulse sequence and inputs the reflection signals to the circulator; the second coupler generates four groups of beat frequency signals according to the local oscillation light and the reflection signal; the data processing module determines vibration phase information according to the beat frequency signal. According to the invention, inter-symbol interference can be suppressed, and the signal-to-noise ratio of the device is improved.

Description

technical field [0001] The invention relates to the technical field of fiber grating sensing, in particular to a distributed vibration measurement device and method based on a weak grating array and pulse coding. Background technique [0002] Phase-sensitive optical time domain reflectometer (φ-OTDR) has the characteristics of distributed sensing, fast response, simple structure, long detection distance and anti-electromagnetic interference. Due to the back Rayleigh scattering in the fiber, the φ-OTDR will be affected by coherent fading, polarization fading and common mode noise, etc., there will be problems such as poor signal-to-noise ratio and sharp drop at the far end. Using a weak grating array, its reflectivity is 2 to 3 orders of magnitude stronger than Rayleigh scattering, and the signal-to-noise ratio of the signal is greatly improved, but there are still common mode noise of the device, light source noise, EDFA spontaneous emission noise, etc. The ratio still need...

AI Technical Summary

Problems solved by technology

[0005] In view of this, it is necessary to provide a distributed vibration measurement device and method based on a weak grating array and pulse coding, which is used to solve the problems existing in the prior art due to the presence of intersymbol interference noise in the decoded beat frequency signal, which will reduce the Coding gain, a technical issue affecting the signal-to-noise ratio of the system

Images